Telephone system



June 17, 1930. I KRECEK I 1,763,893

TELEPHONE SYSTEM Filed Oct. 20 1928 6 Sheets-Sheet 1 ATTOPNEY June 17,1930. J. A. KRECEK 1,753,893

I TELEPHONE SYSTEM Filed Oct. 20, 1928 6 Sheets-Sheet 2 226fllFFERENT/AL MA lNl/EN 70/? J. AKREcEK ATTOPNE Y June 17, 1930. J. A.KRECEK TELEPHONE SYSTEM Filed bet. 20, 1928 6 Sheets-Sheet 5 Fla. 3

MARG/NAL INVEN TOR J. A. Knees/r ATTORNEY June 17, 1930. 4 4 J. A.KRECEK TELEPHONE SYSTEM Filed Oct. 20, 1928 6 Sheets-Sheet 4 /NVEN TOR JA. Knscsk June 17, 1930. J, A. KRECEK 1,763,893

TELEPHONE SYSTEM Filed Oct. 20, 1928 6 Sheets-Sheet s lNl/EN TOR J. A.MPEC'EK ATTORNEY l atentecl June 17, 1930 UNIT rare JOSEPH A. xnnonmorBROOKLYN, NEW YORK, ASSIGN'OR 'ro'EELL TELEPHONE LAE ORATORIES,INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK- TELEPHONESYSTEM This invention relates to telephone exchange systems. Morespecifically it relates to the automatic selection of speech amplifyingapparatus and the insertion of this apparatus between toll lines.

Systems such as those disclosed in Patents No. 1,647,796 issued to L. L.GlezenS. P. ShackletonE. Vroom, November 1, 1927; No. 1,708,982 issuedto E. VroomJ. A. Krecek, April '16, 1929; No. 1,708,983 issued to E.VrooniF. S. Entz, April 16, 1929; No. 1,725,323 issued to E. VroomF. S.Entz, August 20, 1929 and No. 1,738,302issued to J. A. Krecek, December3,1929 have been devised for automatically inserting repeatingamplifiers in line connections. In these applications toll cord circuitsare arranged for discriminating between toll lines that require theaddition of repeaters and toll lines that do not require such anaddition. In general, the arrangement is such that an automaticdiscrimination is made between the two kinds of toll lines, when a cordcircuit is employed to interconnect the lines. Vthon a repeater isrequired this discriminating arrangement functions to start theautomatic selection and connection of the repeater between two lines. Aselecting mechanism or repeater selector is associated with each cordcircuit so arranged as to be automatically started by the discriminatingmeans to search for and seize an idle repeater, a plurality of repeatersbeing provided for the common use of said cord circuits. The repeaterselected by the cord circuit is marked thereby, in order that theselected repeatermaybe identified bythe lines to be connected therewith.Apparatus in the line circuits connected to the cord circuit is operatedin response to the action of the cord.

circuit discriminating apparatus. Thev operation of this line apparatusactuates selectmg switches for the selection of the idle repeater asidentified by the cord circuit markings.

lays are operated and released to form a cir-' cuit combination thatsimultaneously actuates the apparatus of the connected line circuits tosearch for and connect therewith an'idle repeater. A common group ofrepeaters is provided for the lines. Switching apparatus in the outgoingline searches through the group of repeaters for anidle repeater whichis seized when found. Apparatus in the repeater is operatedin responseto this seizure for marking a set of terminals for the repeater finderof the incoming line. An idle finder in a group of finders associatedwith each line is actuated by the incoming line to find said incomingline and find the seized repeater. In re sponse to the foregoing seizureand selection, apparatus in each line is operated to direct thetransmission circuitof the lines through the repeater.

Fig. 1 in its upper portion illustrates two toll line circuits, onerequiring the addition of a repeater and one not requiring suchaddition. A repeater selecting switch is shown in the lower portion ofFig. 1; Fig. 2 illustrates a toll cord circuit with an associatedtelephone circuit. and an amplifying circuit for monitoring purposes. Inthe lower left portion of Fig. 2a timing circuit is shown for use inconnection with the position finder circuit shown in the right lowerportion of this figure.

Fig. 3 illustrates optional line circuits the same as shown in Fig. 1;

4; illustrates two groups of repeater and line finding links, one in theupper portion of the drawing and one in the lower portion;

relay 224 establishes an energizing path for relay 236 from groundthrough contact 1 of relay 224, normal contact of relay 214, normalcontact of relay 220, winding of relay 236 to battery. Relay 236controls supervisory lamp 243 and its function will be hereinafterdescribed. The operation of relay 226 opens the circuit extending torelay 233 in order to place the latter relay under the joint control ofboth interconnected lines.

Atthis time the switchboard operator actuates key 217 for associatingthe telephone set with the incoming line. The actuation of key 217establishes an obvious energizing circuit for relay 202. The operationof relay 202. associates the telephone set transmitter and receiver,through high impedance coil 215, with the incoming line. The operatorobtains the wanted line designation from the calling party and insertsplug 223 into jack 300 of a line such as shown in Fig. 3.

Key 110 is individual to the line and is operated if the line is usedfor an incoming call but is not operated it the line is used "for anoutgoing call. This key may be operated by a transfer operator or by theoperator completing the connection. The operation of key 110 iii-Fig. 1establishes an obvious circuit for operating relay 116, which locksthrou; its contact 1 to ground at contact 1 of relay 118. A circuit isthus prepared for the operation of relay 115 which is eiiective upon acircuit change in the cord circuit when it has found that a repeater isrequired. if a repeater is not required, this circuit change is not madeand the line apparatus remains positioned as previously described untilthe connection is terminated.

The insertion o1 plug 223 into jack 300 establishes a circuit for theoperation of r lays 301 and his circuit may be traced from ground throug1 the winding of marginal relay 302, winding of relay 301, sleeve ofjack 300 and plug 223, winding of relay 227, Wind ing of relay 225, leftwinding of relay 226, contact 1 of relay'229, to battery throughresistance 228. Relays 302 and 227 are marginal and do not operate inthe circuit traced. The operation of relay 301 does not establish anycircuit atthis time. Relay 226 has its windings difi'erentiallyconnected so that the circuit established through its right windingnullilies the effect of the circuit through its left winding. This relaytherefore releases.

When a cord circuit is connected with lines of difierent character thecurrent through the windings of relay 226 is not equalized and thisrelay remains operated. It the outgoing line has a low resistance sleevecircuit with relay 302 omitted, an operating circuit is e tablished forrelay 227. In either case a repeater is not selected. Therefore relays226 and 227 distinguish between lines requiring a repeater and thosethat do not, and thus control circuit changes or either causing arepeater to be selected and inserted between the toll line or forpreventing the selection of a repeater. f

Let it be assumed that a repeater is required betweenthe lines of Figs.1 and 3. -Relay 227 remains normal and relay 226 is 1- leased. A circuitis thus established for operating relay 2331mm battery through itswinding, normal contact of relay 226, normal contact of relay 227,contact 1 of relay 225, contact 2 of relay 22-1 to ground. Relay 233. inoperating establishes a locking circuit for it? self through its contact2, to ground through contact 1" of relay 225 and contact 2 of relay224-. The operation of relay 233 removes battery from a particularterminal associated with brush 26 1 of switch 261. The cord findercircuit 260 and timing circuit 250 are used to prevent a cord circuitfrom being connected to lines longer than an allotted time when an idlerepeater cannot be found. Circuits are also established from therepeater to the cord finder for releasing the cord circuit apparatuswhen a telephone conversation is terminated. This apparatus doesnot,however, serve in locating an idle repeater since the selection of anidle repeater is made by the line apparatus.

The operation of relay. 233 further establishes circuit for operatingmagnet 280 which may be traced from ground through contact 1 of saidrelay, normal contact 4 of relay 232, normal contact '1 of relay 266,contact and winding of stepping magnet 280-, brush 26 1 to batteryconnected to all the terminals excepting the terminal associated withthe cord circuit desiring a connection. /Vhen brush 26% reaches aterminal not connected to battery, the circuit for magnet 230 is openedand relay 270 which has heretofore been shunted by battery on the busyterminals is now permitted to operate. The stepping magnet 280 does notreceive sufficient current when in series with relay 270 to cause itsoperation. Relay 270 in 0 crating .estab lishes a locking circuit for:itself through contact 2 and resistance2ll, Relay 270 also establishesan obvious operating circuit for relay 269. Relay 269 establishes acircuit for operating relay 268 from ground through its contact, windingof relay 268, to battery through normal contact l of relay 2, 2. The

nub

operation of relay 268 establishes an obvious operating circuit forrelay 266. Relay 266 establishes an obvious operating circuit for relay267. At contact 1 of relay 266 the circuit for magnet 280 is opened. Atcontact 2 of relay 266 a circuit is established for relay 231, fromground thr ugh contact 2 of relay 502, and relay 552, or any idlerepeater, extending through brush 262 and the winding of relay 231 tobattery. v

The timing circuit 250 is operated by the association of ground throughcontact 1 of relay 267, contact 1- of relay 255, winding and contact ofstepping magnet 257 to battery through contact 1 of relay 255. When themagnet 257 attracts its armature, relay 255 is permitted to operate forestablishing intern rupte r control for the timing .circuit. The circuitfor relay-255 may be traced from battery through contact 2 of relay'267, winding of relay 255, normal. contacts 3 of-relay 255,

winding of magnet 257 normal contacts 4 of relay 255, to ground throughcontactl of'relay 267. Relay 255 in operating establishes a lockingcircuit for itself through its contact 3 and resistance 256. The brush;assembly is 7 advanced one step and a circuit is established throughcontact 1 of relay 255, winding of re lay 254 and the associatedconstantly rotating interrupter 259 which is intermittently connected toground. to brush 253 through contact 2 of relay 255, for the purpose ofsounding an alarm after a predetermined time interval. Upon each association of a grounded segment of interrupter 259 with the winding ofrelay 254, a

circuit is established for operating the latter relay, since its windingis now connected to batteryat contact 1 of relay 255. The operation ofrelay 254 connects battery through its contact and the winding ofstepping magnet 257 to ground through brush 252 and its as sociatedcontact.

The switch 251 thus continuesto-rotate until brush 253 is associatedwith conductor 258 which will occur unless relay 255 is previouslyreleased.

'Let 1tbe assumed that no idle repeater .available andthat brush 253 isconnected with conductor 258. A circuit is thus es-' tablished fromground at contact 2 of relay 255, through brush 253, conductor 258,contact 4 of relay 267, brush 265 and its associate contact, winding ofrelay 237 to battery. Relay *237 establishes a locking circuit throughits contact 2 to ground at key 240. .Relay 237 further establishes acircuit through its contact 3 to operate relay 238 and lightlamp 239.The operation of relay 238 establishes a' circuit from alternatingsource 242 through bell 241 for sounding an .alarm. Battery isconnectedthrough-conthe release of relay 270. Two sets tactfl of relay 237, brush264 and its associated contact to the winding of relay 270 for releasingrelay 27 O by the shuntmethod. The apparatus of the cord finder circuitand timing circuit is .released in consequence of of relays individualto cord circuits are shownin the V cord finder 260. 1

As previously explained when arepeater is available ground is connectedthrough brush 262 for operating relay 231, and the timing circuit slowlyadvances. Relay 231 in operating establishes alocking'circuit'for itselfthroughits contact 2 to ground through con tact 1 of relay 225'andcontact 2 of relay 224. Relay 231 also establishes an obvious circuitthrough the right winding of relay 229, for

operating the latter relav. The operation of Ground is connected relay229 eliminates resistances 228 and 230 from the circuits previouslytraced through the sleeve relays of the linesin Figs. .1 and 3. Thecurrent flow 'through the sleeve'relays is thus sufficiently increasedto cause the operation of relay 120 of Fig.1 and relay 302 of Fig. 3 foroperating the repeater selecting apparatus of each line.

The incoming and outgoinglines are now simultaneously actuated for theselection of an idle repeater. tus may bev arranged so that eithertheincoming or the outgoing line may be actuated to search for and seizeone end of an idle repeater and mark the other end of'said re-.

peater for selection by the alternate line apparatus. In order toeconomically group the lines and repeaters, it is preferable to operatethe outgoing line apparatus to search for and seize an idle repeater asdisclosed The line circuit apparalay 301. A circuit is. now establishedfor energizing the stepping magnet 321 from battery at contact 4 ofrelay 312, winding and contact of the stepping magnet, normal contact 3of relay 316 to busy groundor battery connected to the contactassociated with brush 323. If-the terminalsassociated with brush 323 arebusy the magnet 321 is 'energized and deenergized for stepping thenon-grounded terminal.- that the first terminal is non grounded. 1Acircuitis thus immediately established for the operation of relay 316,which may be traced from battery at contact 4 of relay 312, through thewinding and contact of magnet 321, winding of relay 316, to ground atcontact3 of relay 312. Relay 316 is shunted by busy grounds and is thusmaintained normal until an idle trunk is found. This busy ground issupplied by relays similar to 316 iniother lines. The operation of relay316 associates busy ground through its contact 3 with brush 323 formaintaining the associated terminal busy.

The brushes of sw tch 320 arerotated according to the foregoingdescription to find an idle trunk, extending between the line and aswitch such as 330. As many switches 33-0 are provided as are necessarymum number of simultaneous calls. The number of such switches may beconsiderably brushes until brush 323 is associated with a et is beassumed for the maxiless than the number of lines and is proportionedaccording to the number of repeaters required in the common group. Whenan idle trunk is found, a circuit is established for the operation ofrelay 337 which may be traced from battery through its winding, brush323 and associate contact to ground at contact 3 of relay 316. Theoperation of relay 337 establishes an energizing circuit for the relay333 which may be traced from ground through contact 341, contact ofrelay 337, normal contact 1 of relay 336, contact of vertical magnet335, contact of the rotary magnet 334 tobattery through the winding ofrelay 333. The operation of relay 333 connects battery through itscontact and the normal contact 2 of relay 332 to the winding of verticalmagnet The energization of the vertical magnet causes the attraction ofits armature which maintains thecircuit for relay 333 opened until thearmature again releases. brushes 343 to 348 are advanced one step. Thevertical magnet armature is released which again causes the energizationof relay 333. The operation of relay 333 again energizes the verticalmagnet which procedure continues until a terminal level is found whichhas an idle repeater connected to a set of terminals in said level. Uponthe first vertical step the vertical 0E normal contacts 338 and 339 areclosed.

The terminals associated with brushes 343 to 348 are divided intolevels, 10 terminals in each level, each terminal of the level beingconnected to a: repeater. If an idle repeater is connected to anyterminal of the level, the segment of commutator 355 associated withthat level is characterized by battery from normal contact 1 of relay501 connected to conductor 512. This conductor is extended to the 10repeaters of the level. If all of the repeaters in a level are busy,battery is removed fromconductor 512 upon the operation of relay 501 ineach repeater. TV hen brush 349 is associated with a battery segment ofcommutator 355, a circuit is established for operating relay 332, frombattery extending over conductor 512, to brush 349, through the leftWinding of relay 332, normal contact 1 of relay 336, contact of relay337 to ground at contact 341. The operation of relay 332 opens at itscontact 2 a circuit for energizing the vertical magnet and establshes acircuit for energizing the rotary magnet 334. Relay 332 also establishesa locking circuit for itself through its right winding and contact 1.The rotary magnet 334 new advances the brushes 343 to 343 step-by-stepin search of the first idle repeater appearing in the level. An id erepeater is characterized by the absence of ground on conductor 511. henan idle repeater is found circuit is thus established for operatingrelays 336 and 501. This circuit may be traced from ground Relay 333 isreleasedand the switch at contact 338 through the right winding ofconductor-511, winding of relay 501 to bat tery. Battery is removed fromconductor 512 by the opening of contact 1 of relay 501 This conductor ishowever extended to the relays of 9 other repeaters connected to thesame terminal level. The segments of commutator 355thus indicate thepresence of idle repeaters in the levels. Relay 336 in operatingestablishes a locking circuit for itself through its left winding andcontact 2, contact of relay 33;- to groundat contact 341. The operationof relay 336 further opens the circuit for the rotary magnet to arrestthe brushes 343 to 343 upon the terminals connected to the idle repeaterand connects a busy ground-through its contact 1 with brush 348. Thelocking circuit for relay 336 furnishes ground for operating relay 331,which connects the conductors fromone end of the idle repeater to theoutgoing line apparatus.

The operation of relay 501 in the selected repeater establishes acircuit through its contact 3 for lighting the filaments of the electrontubes in the repeater. end of the repeater is now designated forselection by the association of battery through contact 1 of relay 501,winding of relay 502 to conductor 514. A segment of commutator 446 isalso'characterized by battery through contact 2 of relay 501, normalcontact 1 of relay 502, and thence over conductor 513 to the lowersegment of commutator 446. I

' It will be remembered that the line apparatus of Figs. 1 and 3 weresimultaneously actuated. The operation of the selecting apparatusassociated with the line in Fig. 1 will now be described. The incomingline because of the operation of relay 116 associates itself with a linksuch as 400 or 450 instead of associating itself with a trunk huntingswitch as shown at 1-40.- The operation of relay 120 establishes acircuit from ground throughits contact and contact 2 ofrelay 116 tobattery through the left Winding of relay 115 for operating the latterrelay. Relay 115 establishes a locking circuit for itself through itsright winding and contact 4 to ground through contact 1 of relay 118.The operation of relay 115 initiates the actuation of'the apparatus inan idle link circuit in a group of links serving the incoming line.Relay 401 in Fig. 4is one of a chain of relays in a link circuit of agiven group. l/Vhen a link has been taken for use, the operation ofrelay401 extends the linkstarting circuit along to another idle link inthe group. Such arrangements are well known in the art and thereforeonly one link in each of two groups has been shown, links 400 and 450being in different link groups. Relay 447 is ener ized from batterythrough its winding, normal contact 5 of relay 114, to ground at contact1 of relay 115. The operation of relay'115 further extends Thenon-selected 7 battery through its contact 2, normal contact4 of relay114 to characterize a segment of commutator 448 as associated with theline taken for use. Battery is further connected at contact 3 of relay115 through the winding of relay-114, to conductor 435 associated withbrush 426 for operating line and link apparatus when the line is foundby the link. A

ground is extended from contact 1 of relay I 118 to contact 50f relay115, for conductor 432', associated with brush 427, for further op- Veration of the link apparatus as explained hereinafter.

The operation of relay 447 extends ground through a chain of relays tobattery through the winding of relay 407 o-fthe first idle link. Theoperation of relay 407 initiates the operation of the switchingapparatus at both ends of the link for selecting the idle repeater takenfor use and the line taken for use.

' Relay 421 is operated for initiating the selectionof the seizedrepeater. The circuit for, operating relay 421 may be traced frombattery through its winding, normal contact of rotarymagnet 420, normalcontact of vertical magnet 419,'normal contact 3 otrelay 418,

contact of relay 407, contact 403, to ground through contact 412. Anenergizing circuit is also established for relay 414 for initiating theselection otthe incoming line; This circuit may be traced from batterythrough its winding, normal contact of rotary magnet 415, normal contactof vertical magnet 416, normal contact 1 of relay 417', contact of relay407, contact 403,'to ground through contact 412. The operation of relays421 and 414 establishes operating circuits'forthe respective verticalmagnets. The circuit for vertical magnet 419 may be traced from batterythrough the contact of relay 421, normal con tact 1 of relay 422,winding of vertical magnet 419, to ground as traced for-the operation ofrelay 421. The energizing circuit for. verticalmagnet 416 maybe tracedfrom battery through the contact of relay 414, normal contact 2 of relay413, winding of vertical magnet 41 6,normalc0ntact 1 of relay 417, toground as traced for the operation of relay 414. The brushes associatedwith both terminal banks and ,commutators arenow stepped yertically forhunting the repeater and line taken for use. Relays 421 and 414 releaseupon each operation of the vertical magnets andare reoperatcd after eachstepis taken.

. WVhen the terminal level is found which in- .1'CltldQSl5l16 repeatertaken for use,a circuit is established for relay 422, which may betraced from groundat contact 412, through contact 403, contact of relay407, normal contact 3 of relay 418, right winding of relay 422, brush440 and the associated segment of commutator 446, conductor 513, normalcontact 1 of relay 502, to battery through contact 2 of relay 501. Whenthe level of terminals is found which includes the line taken vfor use,a circuit is established for the operation of relay 413,

which may be traced from ground at contact 412, through contact 403,contact of relay 407,

normal contact 1 of relay 417, left winding of relay 413, brush 425, andthe segment of commutator 448 associated therewith, conductor 434,normal contact 4 of relay 114, to battery through contact 2 of relay115.

The operation of relay 422 opens the circuit through the wining of thevertical magnet and establishes a circuit for the rotary I magnet 420,which may be traced from battery through the contact of relay 421,contact 1 of relay 422, winding of rotary magnet 420 toground at contact412 as previously traced. Relay 413 also opens the circuit for verticalmagnet 416 and establishes a circuit for rotary magnet 415 which may betraced from battery through the contact of relay 414,contact 2 of relay413, winding of the rotary magnet 415, to ground at contact 412 aspreviously traced. Relays 422 and 413 establish obvious lockingcir'cuitsfor themselves through secondary windings. The brushes 441 to 445 arenow driven in a step-by-step rotary motion to find the terminalsassociated with the selected repeater. Upon each energization of therotary magnet, relay 421 is released and again energizes upon thedeenergization of the rotary magnet. Upon the association of brushes 441to 445 with the selected repeater, 'a circuit is established for relay418 in the link and relay 502 in the V repeater. This circuit may betraced from battery through contact 1 of relay 501,win'd-i ing of relay502, conductor 514, brush 441, left winding of relay 418, to groundthrough contact 409, which contact was closed after the first verticalstep of the switch. The op eration of relay 418 opens the circuit forrotary magnet 420 and establishes a locking circuit for itself throughits right winding and contact 3 to ground at contact 412as previouslytraced. The operation of relay .502

establishes an energizingcircuit for relay 504 which may be traced frombattery at contact 2 of relay 501, through contact 1 of relay 502,

normal contact of relay 505, to ground.

purpose of operating relay 232' at this time is for indicating to thecord circuit that the repeater has been selected by the lines. The

of relay 225' and contact 2 of relay 224 The function of relay 232 willbe hereinafterdescribed in detail.

The line selecting switch brushes 426 to 431 are driven in a stepby-steprotary motion to find the line taken for use, the'rotary magnet andrelay 414 being alternately operated and released upon each step of thebrushes. When the terminals connected to this line are found, a circuitis established for relay 417 in the link and relay 114 in the line. Thecircuit for energizing these relays may be traced from ground at contact406 of the vertical oft-normal contact, which con tact was closed on thefirst vertical step of the switch, through the right winding of relay417, brush 426 and its associate cont-ac conductor 435, winding of relay114, to battery through contact 3 of relay 115. Relay 417 opens thecircuit for the rotary magnet and establishes a locking circuitforitself which may be traced from ground at the Vertical off-normalcontact 406, hrough the left winding contacts 1 and 2 and the rightwinding of relay 417 to battery. The operation of relays 417 and 418establishes energizing circuit for relay 423 which may be traced frombattery at contact 1 of relay 418, winding of relay 423, contact 1 ofrelay 417, contact of relay 407, contact 403 to ground through contact412. The opera- 131011 of relay 423 connects the seized repeater to theincoming line, establishes a circuit for operating relay 401 andestablishes a sec ondary holding circuit for relay 407. he circuit forrelay 401 may be traced from battery through its left winding, contact 1of relay 423, brush 427 and its associated contact, conductor 432,contact 5 of relay 115, to ground at the contact 1 of relay 118. Theholding circuit for relay 407n1ay be traced from battery through itsleft winding to ground over the circuit traced for'relay 401. Theoperation of relay 401 extends the link chain circuit to a link of thegroup which may be seized for a subsequent telephone connection. It willbe seen that the operation of relay 401 opens the energizing circuit extending through the right winding of relay 407. The latter relay,however, remains operated by the establishment of the holding circuittraced through its left winding.

A circuit is established in each line for applying alternating currentthrough the switch contacts for a predetermined period of time in orderto preclude the-possibility of contact resistance from oxidation or afilm of dirt. This alternating current is applied to the switch contactsafter the brushes have beenpositioned. Relay 102 is operated in the linecircuit shown in Fig. 1 from ground through its winding, normal contactof relay 112, to battery through contact- 1 of relay 114. An obviouscircuit is established for operating relay 104 at the same time thatrelay 102is operated. Relay 308 isalso' 437, brushes 431 and 429,contacts Sand 3 of relay 423, brushes 445 and 443 and associatedcontacts, conductors 518 and 516, extending,

through the repeater 500 to conductors 510, and 508, thence throughbrushes 347 and 345, contacts 5 and 3 of relay 331, brushes 327 and 325and their associated contacts, normal contacts 4 and 3 of relay 307 toground through contacts 3 and 4 of relay 303. A

second pair of circuits may be traced from 1 ground at contacts 3 and 4of relay 102, through contacts 3 and 4 of relay 104, thence overconductors 436 and 433, brushes 430 and 428, contacts 4 and 2 of relay423, brushes 444 and 442 and the'associated contacts, conductors 517 and515 through repeater 500, thence over conductors 509 and 507 to brushes346 and 344 and associated contacts, contacts 4 and 2 of relay 331,brushes 326 and 324 and associated contacts. normal contacts 1 and 2 ofrelay 307, to alternating current source 309 througn contacts 1 and2 ofrelay 308,. The alternating currentflowsover the talking conductors andthe switchin'gand relay contacts until the repeater is connectedbetweenthe incoming and outgoing llnes.

The outgoing line has now selected and seized an idle repeater throughswitch 320 and switch 330', and the incoming line has actuated anidlelink 400 which has found the repeater seized by the outgoing line andhas found the incoming line. It wlll be remembered that when the seizedrepeater was 1 found by the link, that a circuit was estal lished foroperating relay 232, which looked to ground at contact 2 of relay 224.Assuming that the keys in the cord circuit are at this time in theirnormal position, acircuit is established for differ ntially releasing'relay 229. This circuit may be traced from ground at contact 1 of relay232, lowermost normal contact of key 221, lowermost normal contact ofkey 213, lowermost normal contact of key 217, to battery through theleft w1nding of relay 229. It will be remembered that V a circuit wasestablished through the right winding of relay 229 from ground atcontact 1 of relay 231.- Since the windings of relay 229 aredifierentially connected, th s relay new releases. ThQQOPGIflt-IOII ofrelay 232 also establishes a circuit for relay 219 which may be tracedfrom battery through the'lower winding of relay 219, lowermost contactof key 217, lowermost contact of key 213, lowermost contact of hey221 toground at con tact 1 of relay 232. The operation" of relay 219opens thetalking conductors between the incoming and outgoinglines.

' may take place between the toll operatorand either subscriber. p Y 1It will benoted that batteryis connected The release of relay 229' againinserts resistanc'es 228 and 230 in series with slee'verelays 120 and302 to cause the release of the latter relays. The release of relay 120establishesa circuit for relay 112 which may be tracedfrom-groundthrough the normal ,contact-ofrelay 120, right winding of relay 112,to-battery through contact 1 of relay @114. 1 Relay 112 in operatingestablishes a looking circuit for itself through its left winding andcontactto battery at contact 1 of relay'114, The operation of this,relay releases relay 102, to disestablish the alter;

nating current cleaning circuit extending 120. One end of the repeaterand the net- 7 work 100 is thus connected to line 180.

In the outgoing line, the release, of relay 302 establishes a circuitfor relay 317 which may be traced. from ground through'nor'mal contactof relay 302, left winding of relay 317 to battery at contact 5 of relay315. Re lay ,317 in operating establishes a locking circuit for itselffrom ground through its rightwmdmgand contactto battery at contact 1 ofrelay 316 and also opens theenergizing circuit for. relay 308. Therelease of relay 308 disestablishes the alternating our- 7 rent cleaningcircuit traced through its contacts. The release of relay308 also establishes a circuit for relay 310 which" may be traced from ground at thenormal contact of relay 302, normal contact 5 of relay 308, winding ofrelay 310, to battery at contact 2 of relay 316. The operation of relay310*con- I 'nects the alternate end of the repeater and network 311 tothe outgoing line;

The operation of the talking 'key 217 or ringing keys 213 or 221 opensthe circuit through thewinding of relay 229 and through the winding ofrelay 219. The operation of.

any of these keys tlius causes the operation j 'of relay 229 for openingthe circuit between the repeaters and the lines, andfalso causes therelease of relay'219 in order that talking through contact 3 of relay232 tobrush 264 .and its associate contact, winding ofrelay 270, formaintaining the switch point busy.

and for permanently shunting relay 270. The

release of relay 270 causes the release of relays 269, 268,- 267 and 266which arrestthe movement of the time alarm'circuit 250 and causes thealarm circuit switch to restore tots normal position.

, V The restoring circuit maybe traced from'battery through thenormalcontact-1 of relay, 255, contact and windductors for oper 1,7es;ses

ing of thesteppingmagnet 257'to ground associated with brush 252.

The supervismg of the toll lines is accomplished in approximatelythesame manner as in tollcord circuits well known in-the art. Relay 236 ismaintained operated from battery through" its'winding, normal contact ofalternating current relay 220, normal contact of alternating currentrelay 214 to ground at contact 1 of relay 224. Lamp 243 thereforeremains extinguished unlessa signal is transmitted over. the incoming oroutgoing toll lines. A signal transmitted; over the incominglineoperates relay 214 anda' signal, transmitted over the outgoing tollline operates relay 220. The operation of either one of these relayscauses the'release of relay 236, which provides an operating circuit forrelay 235. This circuit maybe traced from battery through the winding ofrelay 235, normal contact of relay 236 to ground atcontact 1 ofrelay224. The operation of relay 235 provides a circuit from battery throughthe winding of relay-234 to ground at contact 1 of relay 224. An obviouscircuit is thus established to light lamp 243. Relay 234 in operatingestablishes alocking circuit for itself through its contact 2 to groundat the uppermost contact. of the talking key 217.

The switchboard operator upon notingthe.

signal operates the talking keyrfor-associating h'ertelephone set witheither line.

tion of thetalking keyopens the locking ClI-';

It will be remembered that relay" 219 releases when a talking key isoperated. The operacuit for relay234 whichreleases and extinn guisheslamp 243.

Upon the termmation of a conversation the operator presiding over thecord circuit, Fig. 2, 1s given a disconnect signal by the toll op-,erator who originated the call. This operator applies ringing currentto the line. conating relay 214 for lighting lamp 243 as previouslydescribedL'Atlthis time plugs 211 and2231are removed from jacks 108 and300 respectively. "The relays of the cord circuit and the incoming andoutgomg line circuits are thus restored tofnormal. Switches 261 and 320are not restored to normal and are advanced tromfthe position in whichthey are. resting when usedifor a subsequent telephone connection."Uponthe release of relay 316 thecircuit forrelay 337 f is opened whichcauses the release of the lat-- ter relay. The release of relay 337establishes may be'traced from ground-at contact 341, through the normalcontact ofrel'ay 337, vertical off-normal contact 339, winding ofre-.leasemagnet 340,'to battery. Switch 330'is thus caused to restorebrushes 343 ;to 349.1;0 their normal position. The circuit formainfltainingrelay 501 of the repeater isthus opened which relay releasescausing the release of the remaining relays of the repeater.

a circuit for the releasemagnet 340- which 1 The apparatus of link 400is released at approximately the same time as the apparatus of switch330. It will be remembered that relay 407 was maintained in operationover a circuit extending through its left winding oil-normal contact408, normal contact of relay 407, contact 403 to ground at contact 412.The brushes 425 to 431 and 440 to 445 are thus restored to their normalposition and the remaining relays of the link are released.

IVhat is claimed is:

1. In a telephone exchange system, lines of different characteristics, alink, means in said link for interconnecting said lines, a

group of repeaters, automatically operable.

means in said link for determining the character of the lines with whichit is connected, switching means in interconnected lines of a particularcharacter operable in response to the said determining means to searchfor and seize an idle repeater and means in said lines for directing thetransmission circuit of said lines through said seized repeater.

2. In a telephone exchange system, lines having switching apparatusassociable therewith, a link, means in said link for interconnectingsaid lines, a group of repeaters, means in said link operable inresponse to the interconnection of two of said lines to cause theapparatus of one line to search for and seize an idle repeater and causethe apparatus of the alternate line to select said seized repeater, andmeans in said lines operable in response to said seizure and selectionfor directing the transmission circuit of said lines through said seizedrepeater.

3. In a telephone exchange system, lines having switching apparatusassociable therewith, a link, means in said link for interconnectingsaid lines, a group of repeaters, means'in said link operable inresponse to the interconnection of two of said lines to simultaneouslyactuate the apparatus of both lines to cause the apparatus of one lineto search for and seize an idle repeater, and cause the apparatus of thealternate lineto select said seized repeater, and means in said linesoperable in response to said seizure and selection for directing thetransmission circuit of said lines through said seized repeater.

4. In a telephone exchange system, lines of different characteristics, alink, means in said link for interconnecting any two of said lines, agroup of repeaters-,means in said link operable in response to aninterconnection of linesof a particular character to cause the apparatusor" one of said lines to search for and seize an idle repeater and causethe ap paratus of the alternate line so connected to select said seizedrepeater and means in said lines responsive to said seizure andselection for directing the transmission circuit of said lines throughsaid seized. repeater.

5. In a telephone'exchange system, lines of different characteristics,switching apparatus associable with lines of certain characteristics, alink, means in said link for interconnecting any two of said lines, agroup of repeaters, means in said link operable in response to aninterconnection of two lines of said certain characteristic, tosimultaneously actuate the switching apparatus of i said interconnectedlines to cause the switching apparatus of one line to search for andseize an idle repeater and the switching apparatus of the alternate lineto selectsaid seized repeater, and means in said lines responslve tosaid seizure and selection for directing the transmission circuit ofsaid lines through said seized repeater.

6. In a telephone exchange system, lines having a hunting switch and agroup of finders associable therewith, a link, means in said link forinterconnectingtwo of said lines, a group of repeaters, means insaidlink operable in response to the interconnection of said lines tosimultaneously actuate the apparatus of said two lines to cause thehunting switch in one line to search for and seize an idle repeater andcause an idle finder in said group to associate itself with thealternate line and connect said alternate line with the seized repeaterand means in said lines responsive to the connection of said lines tosaid repeater for directing the transmission circuit of said linesthrough said seized repeater.

7. In a telephone exchange system, lines of different characteristics, acord circuit .for interconnecting said lines, repeaters, automaticallyoperable means in said cord circuit for determining the character of thelines with which it is connected, means associable with one of twointerconnected lines of a particular character operable in response tosaid first means and independent of further cord circuit control forselecting and seizing an idle repeater, means associated with a secondone of two interconnected lines of a particular character responsive tosaid first means and independent offurther cord circuit control forselecting said seized repeater, and means for including said seizedrepeater in series with the talking conductors of said two lines.

8. In a telephone exchange system, an office, a plurality of two-waytrunk lines extendingbetween said ofiice and a plurality ofotheroffices, means for lnterconnectmg said trunks, repeaters, meansfor, searching fora-11d selzlng an idle repeater, means for selectingsaid seized repeater, and means' inv each trunk responsive to a saidinterconnection for connecting with said searching means or saidselecting means according. as said trunk is used as an incoming trunk ori an outgoing trunk.

9. In a telephone exchange system, an office, a'plurality of two-waytrunk lines ex tending between said ofliceand a plurality of other'ofiices, means for mterconnectlng said trunks, repeaters, ineansforvsearchlng ing means, other means in each trunk for confor and seizingan idle repeater, means for selecting said seized repeater, means ineach trunk responsive to a said interconnection ror connecting with saidsearching means or said selecting-means according as said trunk is usedas an incoming trunk or an outgoing trunk, and means for indicating tosaid con:

necting means whether said trunk is used as an incoming trunk or anoutgoing trunk.

10. In a telephone exchange system, an ofv I fice, a plurality of trunksextending between said oifice and a plurality of other offices,

said trunks being arranged for use either as repeater, connecting meansin each trunk reincoming trunks or outgoing trunks, means forinterconnecting said trunks, repeaters, means for searchlng for andselzlng an idle repeater,means for selecting a said seized sponsive to asaid interconnection forconn'ectl'ng WlthSL-ld searchmg means, otherconnecting means 1n each trunlcfor connectwith said selecting means, andmeans for operating said first connecting means if said trunk isemployed as an outgoing trunk and foroperating said other connectingmeans if "said'trunk is employed as anincoming trunk.

11. In a telephone exchange system, an oiii'ce, a plurality oftrunksextending between said oflice and a plurality of other offices,said trunks being arranged for use either as incoming trunks or outgoingtrunks, 7 'means for lnterconnecting said trunks, re-

peaters, means for searching for and seizing an idle repeater, means forselecting a said seized repeater, ,means in each trunk responsive tosaid nterconnectlon for connecting with said searching means, othermeans for searching for and seizing an idle repeat- I means in eachtrunk responsive to said'interlecting means, and means to determinewhich connecting means shall be GlIGCtlVG.

in each trunk for connecting with said se- 12. In a telephone exchangesystem, an office, a plurality of trunks extending between saidofiiceand aplurality of other oiiices, said 1 trunks being arranged for useeither as incoming trunks or outgoing trunks, means for interconnectingsald trunks, repeaters, means er, means for selecting a said seizedrepeater,

connection for connecting with said search-

